1. Field of the Invention
This invention relates to a stopper for a medical container. More particularly, it relates to a stopper for a medical container, which can tightly close an opening of the medical container body such as a vacuum blood collection tube and can be pierced with a needle and which can further prevent the liquid in the medical container from leaking through the puncture formed therein by piercing.
2. Description of the Prior Art
Heretofore, as the stopper for a medical container which tightly closes an opening of the medical container body such as a vacuum blood collection tube and can be pierced with a needle, the stopper made of vulcanized butyl rubber had found popular adoption because it excels in various properties such as low permeability to gas, thermal stability, and chemical resistance, possesses sufficient elasticity, and suffers only from small permanent set.
Even when the stopper of vulcanized butyl rubber which possesses sufficient elasticity and suffers only from small permanent set is used, the liquid held in the medical container inevitably leaks through the puncture formed by piercing at the time that the needle is drawn out of the stopper.
In collecting blood by a vacuum blood collection tube 101, for example, the vacuum blood collection tube 101 which is formed by tightly plugging an open end 103 of a cylindrical body 102 of the tube 101 with a stopper 104 made of vulcanized butyl rubber and sealing a prescribed gas in the cylindrical body 102 and keeping the gas under a prescribed degree of vacuum is inserted, with the open end in the lead, into a blood collection tube holder 111 which is closed at one end thereof and opened the other end thereof and has a blood collection needle 110 helically fitted into a threaded hole 109 at the closed end 108 as illustrated in FIG. 6. This blood collection needle 110 comprises a blood vessel piercing part 110a and a stopper piercing part 110b, with the stopper piercing part 110b sheathed with a rubber tip 112. Then, the blood vessel piercing part 110a of the blood collection needle 110 is thrust into the blood vessel such as, for example, the vein and the vacuum blood collection tube 101 is inserted with pressure into the closed part 108 of the blood collection tube holder 111. As the result, the stopper piercing part 110b of the blood collection needle 110 pierces the rubber tip 112 and the stopper 104 and the leading end of the part 110b reaches an inner space 105 of the blood collection tube 101. Owing to the negative pressure inside the inner space 105, the blood in the blood vessel flows into the inner space 105 of the blood collection tube 101 to an extent equalling the degree of vacuum involved. Subsequently, the vacuum blood collection tube 101 is removed from within the blood collection holder 111. Finally, the blood vessel piercing part 110a of the blood collection tube 110 is removed from the blood vessel to complete the collection of blood. Then, when the vacuum blood collection tube 101 is removed from within the blood collection tube holder 111, the blood collection needle 110 which has pierced the stopper 104 and reached the interior of the vacuum blood collection tube 101 is pulled out of the vacuum blood collection tube 101. At this time, as the blood collection needle 110 is pulled out, portion of the blood held inside the blood collection tube 101 passes through the puncture formed in the stopper 104, spills on an upper surface 104b of the stopper 104, and forms a pool of blood 114 on the upper surface 104b as shown in FIG. 8. It is inferred that this leakage is caused because the blood collection needle 110 draws in the blood at the time that it is pulled out. Besides, the possibility that the interior of the blood collection tube 101, on completion of the collection of blood, will assume a positive pressure equalling the venous pressure is considered to be another cause for the leakage.
The fact that the liquid held inside the medical container is suffered to leak and adhere to the outer side of the stopper is nothing to be desired because it has the possibility that a worker engaging in clinical test, on accidentally touching the medical container, will be polluted with the liquid adhering to the outer side of the stopper.
This invention, therefore, aims to eliminate the problems encountered by the conventional stopper for the medical container as described above.
To be specific, an object of this invention is to provide an improved stopper for a medical container.
Another object of this invention is to provide a stopper for a medical container which can tightly close an opening of the medical container and can be pierced with a syringe and which has no possibility of leakage of the liquid from the medical container through the puncture formed therein by piercing.
A further object of this invention is to provide a stopper suitable for plugging a vacuum blood collection tube.